Various network protocols are used to provide networking services to devices. For example, DHCP (Dynamic Host Configuration Protocol) allows the dynamic assignment of IP (Internet Protocol) addresses to hosts. Network protocols such as DHCP are often implemented using a client-server model in which protocol clients request services from protocol servers, which in turn provide the requested services in accordance with the network protocol. For example, in DHCP, a DHCP client may request an IP address from a DHCP server. In response, the DHCP server sends a reply assigning an IP address to the requesting DHCP client. Thereafter, the DHCP client uses the assigned IP address in a manner consistent with the protocol.
DHCP provides advantages including facilitating access control and traffic restrictions on an individual DHCP host basis, in contrast to IP port security that can be used in the case of static hosts (hosts with static IP addresses), which can only restrict the number of static hosts allowed on each access port but which cannot apply any particular individualized access control policy for each individual static host.